1. Field of the Invention
The present invention relates to an electroacoustic transducer adapted for reflow soldering and an electronic equipment using the same.
2. Description of the Prior Art
Conventionally, an electroacoustic transducer is mounted in a small-sized electronic equipment such as a portable telephone, a pager unit as a notification means. The electroacoustic transducer mounted in such electronic equipment is small-sized in itself, and constituting parts thereof are miniaturized. Further, electric connections of the electroacoustic transducer with the electronic equipment is performed by reflow soldering. The reflow soldering is a method to permit portions to be joined together to pass through heated and fused solder so as to solder the same. Reflow temperature is high to the extent of about 300.degree. C. and reflow heat is also applied to a portion other than the portions to be joined, particularly a coil of a magnetic driving portion of the electroacoustic transducer is exposed to heat generated by the reflow soldering.
Whereupon, there are a bobbin type coil and a bobbinless type coil as the form of the coil installed in the magnetic driving portion. In the electroacoustic transducer which is needed to be small-sized, employment of the bobbinless type coil is dominating. This is caused by the fact that a space to be occupied by the coil in the electroacoustic transducer is narrowed. It is necessary to increase the ratio of space occupied by the coil itself so as to assure sufficient number of windings of the coil in the narrow space. The bobbinless type coil is realized also by the employment of a fusion type wire for forming the coil.
Whereupon, when the reflow soldering is performed on the electroacoustic transducer, heat generated by the reflow soldering deforms the coil, especially increases the height of the coil. As a result, it influences upon not only the shape thereof but acoustic characteristic so as to deteriorate the acoustic characteristic such as change of generated sound, whereby the quality of final product is likely to be deteriorated. Accordingly, the bobbin type coil is forced to be used. Further, it is necessary to take a measure to perform the soldering at a reflow temperature as low as possible.